Since the yeast will burn sugar away generating alcohol & CO2 for as long as it can (until the % by volume makes the brew toxic, killing the yeast off), just adding more sugar doesn't seem to the answer.

Although this technically results in a sweeter (sugar remaining after yeast is no longer viable) result, carbonation drops won't work to carbonate in bottles.

How do you get a sweeter result?

For example mead or ginger ale are typically quite sweet; how is this achieved?

Is there some kind of sugar which is not compatible with certain yeast strains?

5 Answers
5

To get residual sweetness without knocking out the yeast, you add non-fermentable sugars to the wort. To add sweetness and some body in an extract brew, lactose is the usual adjunct: 1/8 to 3/8 pound in a 5 gallon batch gives a noticable sweetness. As lactose is non-fermentable, it can be used to adjust the sweetness either by adding to the boil, or at bottling time. Similarly, Maltodextrose can also be added, although this is pretty much tasteless, and adds no sweetness, just body.

In partial mash/all grain brews, adding 1/4-1 lb of light crystal (10L or less), such as carafoam/carapils will also leave a residual sweetness without contributing much color or other flavors. Darker crystals will darken the color and also add caramel flavor, and the darkest types (120L+), add dark sugar, toffee, or plum/raisin flavors.

When using non-fermentables to create residual sweetness, the yeast have not been overwhelmed by the alcohol, so you can continue to prime and carbonate in the bottle as usual.

1/8 of a pound of lactose isn't going to make the beer taste sweeter. in 5 gallons even a 1/3 of a pound is barely noticeable.
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brewchezJan 17 '12 at 0:34

I've added 1/4 pound to a juleøl and noticed it considerably. I agree 1/8 would be barely noticeable in a typical milk stout, but it depends upon the beer, and how bitter it presently is - I think 1/8th would be clearly noticable in a light pale ale.
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mdma♦Jan 17 '12 at 0:41

To my palette I've titred down to 1/8th in water and it wasn't sweet to me. Lactose itself just isn't that sweet even on its own.
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brewchezJan 17 '12 at 2:26

There are a few techniques for making beer a little sweeter. If you're an all-grain brewer, mashing at a higher temperature leaves your wort a little less fermentable, which will leave more residual sweetness. Since brewer's yeast won't break down lactose very well, adding a little lactose will make your beer sweeter. Also, adding specialty grains such as crystal malt will add sweetness.

One way you get a sweet mead is to just add a LOT of honey. Once the alcohol content gets high enough, the yeast will die off leaving behind the sweetness.

The easiest, most direct way to get a sweeter beer is to use less hops, particularly the bittering addition, although other hop additions can contribute to the perception of bitterness. You can also increase the chloride and/or sodium levels in the water to increase the malty character. Just be careful not to overdo the sodium.

If you want to make a sweet fermented beverage, you need to do something to disable the yeast, so sugar can be added without fermenting.

As others have pointed out, sweet mead is made by adding enough honey to bring the ABV above the yeast's tolerance level, and killing it. Then honey can be added without risk of fermentation to bring the sweetness level up.

Fermented ginger all ale is typically cold-crashed while there is remaining unfermented sugar. The cold temperatures disable the yeast, and the beer remains sweet.

The third way is to chemically disable the yeast. The correct dose of potassium sorbate and metabisulphite will knock the yeast out and you can sweeten to your heart's content.